"I'm smaller than I was in high school!"

Thirty-four-year-old DJ Gray was an emotional eater. Crushed by the pressure of running a day-carebusiness and working weekends as a nurse's aide—not to mention being the mother of four kids—the Lilly, Pennsylvania, native would soothe herself with plates of meatloaf and mashed potatoes. The comfort food, plus her mostly sedentary lifestyle, left DJ, 5'3", weighing in at 220 pounds.

The Change: In October 2012, DJ discovered a lump in her breast and feared she had breast cancer, which runs in her family. Her tests came back negative, but the scare prompted her to take a hard look at her health. "The doctor said the mass could be due to my weight gain," she says. "I knew if I wanted to be around for a long time, I needed to change things."

The Lifestyle: DJ bought a food scale to help her prepare portion-controlled meals. "I used to eat three bowls of granola at a time," she says. "Now I know what's a healthy amount." She wrote down everything she ate and tracked calories with a mobile app (her goal: 2,000 a day). She gradually weeded out fried foods, sugary cereals, and extra desserts from her diet. In two months, DJ dropped 20 pounds. Inspired, she started exercising daily—using the elliptical machine gathering dust in her basement, doing workout videos, and taking Zumba classes—and shed another 60 pounds in four months. In May 2013, her son was in an accident, and she gained back 10 pounds due to stress and a lack of workout time. To bounce back, she started running the length of her street, 1.2 miles, every other day—and soon was adding laps. She dropped those 10, plus a little more, hitting 131 by June.

The Reward: DJ says her whole system is rewired: She recently took a bite of a chicken nugget and spit it out! "It doesn't even taste good anymore,'' she says. She loves shopping for clothes—and buying tops she couldn't have fit into as a teenager (She's gone from a double-D bra to a proudly perky B.) DJ ran her first 5-K in September, crossing the finish line seventh in her age group. "I never believed I'd be able to do this much," she says.

Fit it in. "Even if it's 11 p.m., there's always time to move around more."Remix your fix. "I gave up sweet tea and have hot tea with Splenda instead, which tastes just as good."Treat yourself. "If I meet a goal, I get my nails done or buy a new pair of shorts."